Feed roll abrasion roller

ABSTRACT

An apparatus in which an abrasive member is positioned in rubbing engagement with a moving separating and advancing means of a sheet forwarding mechanism to retain a preselected frictional force between the separating and advancing means and successive single sheets for permitting the efficient separation and advancement thereof. The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to be limiting as to the scope of the invention in any way.

United States Patent 1 Guenther [451 May 8,1973

[54] FEED ROLL ABRASION ROLLER [75] Inventor: Joachim Guenther, Webster,NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: Nov. 8, 1971 [21] Appl. No.: 196,691

[52] U.S.Cl. ..271/36,27l/21,271/5l [51] Int. Cl. ..B65h 3/06 [58] Fieldof Search ..27l/36, 37, 38, 39, 271/40, 41, 21, 22, 23, 51, 52,19, 24,42, 64

[56] 3 References Cited UNITED STATES PATENTS 984,273 2 1911 Hebert..271 37 1,668,967 5/1928 Labombarde ....27l/37 1,956,475 4/1934Robinson ..271/39 X Primary Examiner-Ev0n C. Blunk AssistantExaminer-Bruce H. Stoner, Jr. Attorney-James J. Ralabate et a1.

[57] ABSTRACT An apparatus in which an abrasive member is positioned inrubbing engagement with a moving separating and advancing means of asheet forwarding mechanism to retain a preselected frictional forcebetween the separating and advancing means and successive single sheetsfor permitting the efficient separation and advancement thereof.

The foregoing abstract is neither intended to define the inventiondisclosed in the specification, nor is it intended to be limiting as tothe scope of the invention in any way.

9 Claims, 1 Drawing Figure PATENTEDMY 81m 3.731.915

- INVENTOR JOACHIM GUENTHER ATTORNEY FEED ROLL ABRASION ROLLERBACKGROUND OF THE INVENTION This invention relates to an apparatus formaintaining a sheet forwarding mechanism in condition to efficientlyseparate and advance a sheet from a stack of sheets, and moreparticularly concerns an apparatus for engaging the moving separatingand advancing means of the sheet forwarding mechanism to retain apreselected frictional force between the separating and advancing meansand each successive sheet to be forwarded therefrom.

It is customary to provide a sheetmaterial, such as paper, for typicalcopiers used in business offices. Generally the paper is of apredetermined size which advances through the copier, one sheet at atime, for suitable processing therein. Inasmuch as copies may be made athigh speed, it is advantageous to stack a usable supply of paper in asheet forwarding mechanism and to automatically advance one sheet ofpaper at a time to the sheet processing apparatus of the copier.

A conventional sheet forwarding mechanism is equipped with a tray memberthat supports a stack of sheets, separator elements at the forward endof the tray member, and a feeding mechanism having one or a plurality ofrotatable feed rolls for separating and advancing the paper. The feedrolls engage the surface of the sheet to be separated and advanced fromthe stack. As the feed roll rotates, a frictional force is applied tothe sheet of paper which separates and advances the sheet from theremainder of the stack. The surface of the feed roll engaging successivesheets must have a coefficient of friction which is sufficiently high toseparate and advance successive sheets therefrom. Generally, if thecoefficient of friction of feed roll surface is within a preferablerange, the feed roll will operate efficiently. However, after prolongedusage the feed roll surface gradually becomes progressively smoother.This results in a progressive decrease in the coefficient of frictionthereof, and, inasmuch as the normal force applied thereto during eachsheet forwarding cycle is substantially constant, an ensuing reductionin the frictional force exerted on the sheet results. When thefrictional force decreases beneath a critical value, the feed roll willsporadically slip on the surface of the sheet and no longer efficientlyseparate and advance successive sheets therefrom. Heretofore, thetypical natural rubber feed roll was capable of separating and advancingabout 20,000 sheets before sufficient slippage occurred between the feedroll and sheet to prevent the efficient separation and advancementthereof.

Progressive glazing" of the feed roll surface is the primary factor inreducing the coefficient of friction thereof. Glazing of the feed rollsurface is usually produced by contamination or waste material becomingembedded therein. In office copiers, such as xerographic machines, thecontaminants usually are in the form of paper fibers, e.g., titaniumdioxide, a paper whitener, and/or toner particles. When, due to glazing,the coefficient of friction has decreased below the critical value, thefeed roll starts to slip and eventually fails to perform the sheetseparation and advancement function satisfactorily.

Another problem associated withfeed rolls fabricated from natural rubberis the deleterious deterioration thereof. Feed roll deterioration isdue, primarily, to the reaction of the natural rubber with ozone whichis normally present in xerographic copiers requiring high electrostaticfields in the operation thereof. Although the amount of ozone producedis relatively low, it nevertheless is sufficient, after a period oftime, to harm the feed roll.

Accordingly, it is a primary object of the present invention to improvethe efficiency of a sheet forwarding mechanism byextending the usefullife of the separating and advancing means thereof.

SUMMARY OF THE INVENTION Briefly stated, and in accordance with thepresent invention, there is provided an apparatus for maintaining abouta preselected frictional force between the separating and advancingmeans of a sheet forwarding mechanism and each successive sheet to beforwarded thereby.

In accordance with the present invention, the apparatus includes anabrasive member mounted movably in a support member. The support memberis adapted to move the abrasive member into rubbing engagement with theouter surface portion of the separating and advancing means. In thisway, the abrasive member maintains the outer surface potion of theseparating and advancing means substantially free from contamination andat about a constant roughness to retain the preselected frictional forcebetween each successive sheet and the separating and advancing means.This insures that each sheet is efficiently separated and advancedduring the useful life of the mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of thepresent invention will become apparent upon reading the followingdetailed description and upon reference to the drawings, in which theFIGURE illustrated is a perspective view depicting the apparatus formaintaining the separating and advancing means of the sheet forwardingmechanism at substantially a constant roughness.

While the present invention will be described in connection with apreferred embodiment, it will be understood that it is not intended tolimit the invention to that embodiment. On the contrary, it is intendedto cover all alternatives, modifications and equivalents as they beincluded within the spirit and scope of the invention as defined by theappended claims.

DETAILED DESCRIPTION OF THE INVENTION With continued reference to thedrawing, a sheet forwarding mechanism is illustrated as having anabrasive member therein for maintaining a preselected frictional forcebetween the feed rolls thereof and successive sheets to be forwardedthereby. The abrasive member continuously engages the surface of thefeed rolls to remove contaminants and maintain the roughnesssubstantially constant during the operation of the sheet forwardingmechanism. This, in turn, insures that there is no slippage andsuccessive sheets are separated and advanced from the sheet forwardingmechanism.

The sheet forwarding apparatus, indicated generally by the referencenumeral 10, includes a tray member,

designated generally at 12, for holding a stack of sheet material, apair of feed rolls l4 and 16 for separating and advancing successivesingle sheets from the stack, a registration member 18 for aligning theforwarded sheet, forwarding rolls 20 and 22 for advancing the sheetafter alignment. Feed rolls 14 and 16 are mounted in cooperatingrelationship with one another in front of tab members 24 and 26 whichassist in separating the forwardly moving paper from the remainder ofstack 28. Feed rolls l4 and 16 advance the uppermost sheet of stack 28over tab members 24 and 26, and between forwarding rolls 20 and 22,until the leading edge potion of the forwarded sheet engagesregistration member 18. This is achieved by a suitable endless belt orchain drive 30 which rotates cam 32 in the direction of arrow 34. Sectorgear 36 is resiliently maintained in engagement with cam 32 by means ofa suitable spring member 38. Cam 32 drives sector gear 36 in anoscillating fashion as indicated by arrow 37. Sector gear 36 meshes withpinion gear 40 to rotate pinion gear 40 in counter clockwise andclockwise directions. Since pinion gear 40 and feed rolls 14 and 16 aresecured to common shaft 42, feed rolls 14 and 16 rotate in conjunctionwith pinion gear 40 as indicated by arrow 44. Feed rolls 14 and 16 arein intermittent rotation, and are adapted to engage the uppermost sheetof stack 28 disposed in tray member 12. Tray member 12 includes apivotable base plate 46 on which the stack 28 is disposed. Base plate 46is adapted to pivot so that the uppermost sheet of stack 28 engages feedrolls l4 and 16. Drive 30 rotates shaft 48 having cam 50 mountedthereon. Cam 50, in turn, drives cam follower 52, which is mounted on acommon shaft 54 with tab members 24 and 26. Tab members 24 and 26,thereby, pivot in synchronism with feed rolls l4 and 16 to engage anddisengage the uppermost sheet of stack 28 at the appropriate time, i.e.,shaft 54 rotates in both a clockwise and counter clockwise direction asindicated by arrow 56. Forwarding roll 22 is rotated by a suitable drive(not shown). Cam 58 drives cam follower 60, which, in turn, causesconnecting link 62 having shaft 66 and shaft 68 affixed thereto, topivot in the direction of arrow 64. In this way, shaft 66, which hasforwarding roll 20 mounted thereon, is adapted to move forwarding roll20 into and out of en'- gagement with an advancing sheet passing overforwarding roll 22. The advancing sheet moves between the closely spacedforwarding rolls 20 and 22, and the leading edge potion engagesregistration member 18, Registration member 18 is adapted to move inupwardly and downwardly directions, as indicated by arrow 39. Link 62pivots to move forwarding roller 20 downwardly into engagement with theadvancing sheet, and simultaneously therewith, registration member 18downwardly to disengage the leading edge potion of the advancing sheettherefrom. The sheet is, thereupon, transferred from the sheetforwarding apparatus 10. It will be appreciated that the operation ofthe sheet forwarding apparatus is controlled by driving means 30, which,in turn, is controlled by a suitable timing apparatus to insure theproper sequential advancement of the forwarded sheets.

Upon inspection of the FIGURE, it will be seen that tray member 12includes a gate member 13 mounted pivotably thereon at one end thereofvia hinge pin 15.

Gate member 13 is adapted to pivot about 3 or 4 in substantially acounter clockwise direction into engagement with feed rolls 14 and 16.

Having observed the details of the operation of sheet forwardingmechanism 10, attention may now be given to the specific subject matterof the present invention, an apparatus, designated generally at 70, forengaging feed rolls 14 and 16 to maintain surfaces 14a and 16a,respectively, at a substantially constant roughness and to removecontaminants therefrom. This, in turn, insures that the frictional forcebetween successive sheets and feed rolls l4 and 16 remains at about thepreselected value. Apparatus 70 includes a support member, indicatedgenerally at 71, and an abrasive member, designated generally at 78.Support member 71 has a shaft 72 mounted in sheet forwarding apparatus10, and a pair of coupling members 74 and 76 attached pivotably to shaft72. Coupling members 74 and '76 have abrasive member 78 interposedtherebetween and mounted rotatably therein. Abrasive member 78 includesshaft 77 interposed between and mounted rotatably on coupling members 74and 76. Shaft 77 comprises a cylindrical member 80 having frictionalmeans 82, such as a coating of sandpaper, affixed thereon. In addition,biasing means 84, for example, a coil spring, is adapted to preventcylindrical member 80 from rotating in one direction while permittingcylindrical member 80 to rotate in the other direction. Coil spring 84has one end thereof attached to coupling member 74 and is wound aboutshaft 77 with the other end thereof attached to cylindrical member 80.Spring 84 is prewound and yieldingly prevents feed rolls 14 and 16 fromrotating abrasive member 78 in one direction. However, abrasive member78 is free to rotate in the opposed direction. In this manner feed rollsl4 and 16 abrasively slide over sandpaper coating 82 to removecontaminants therein and maintain the roughness thereof substantiallyconstant. Spring coil 84 is prewound such that cylindrical member 80rotates freely when feed rolls 14 and 16 rotate counter clockwise tobuckle the uppermost sheet of stack 28 for separation thereof while ityieldingly prevents rotation of cylindrical member 80 when feed rolls l4and 16 rotate in a clockwise direction to advance the uppermost sheet ofstack 28 therefrom.

Furthermore, it will be appreciated that coupling members 74 and 76 aremounted pivotably on shaft 72. In this manner, coupling members 74 and76 having cylindrical member 80 interposed therebetween are pivoted insubstantially a downwardly direction under the force of gravity tolocate sandpaper coating 82 in engagement with surface portions and 16aof feed rolls l4 and 16, respectively. When feed rolls l4 and 16 rotatein a clockwise direction, surface portions 14a and 16a thereof are movedacross the substantially stationary sandpaper coating 82. Sandpapercoating 82 abrades surface portions 140 and 16a of the respective feedrolls 14 and 16 and prevents glazing of these surfaces. Moreover, thedeleterious deterioration of the feed roll caused by ozone is minimizedby the continuous removal of material therefrom by abrasive member 78.

By way of example, the feed rolls are preferably an elastomer such asnatural rubber, synthetic rubber or Mearthane, and have a coefficient offriction preferably ranging from about 2.36 to about 2.97. Preferably,the sandpaper coating 82 affixed to cylindrical member 80 minimizes theamount of material removed from the natural rubber feed roll whileinsuring that the coefficient of friction is maintained substantiallyconstant. An appropriate grit sandpaper must be judiciously selected. Aninappropriate selection such as type 325 sandpaper coating causes adiameter decrease of about 0.014 inches in the feed rolls afterforwarding 25,000 sheets, or 0.070 inches thereof after forwarding125,000 sheets. in addition, when type 325 sandpaper was used, smallrubber particles tended to abrade from the feed rolls and interfere withthe operation of the sheet forwarding apparatus. Whereas a suitableselection such as a type 600 sandpaper coating maintained thecoefficient of friction at about 2.97 after forwarding approximately50,000 sheets without any recordable change in the diameter of the feedroll. After forwarding 100,000 sheets the coefficient of friction wasonly reduced by about 4 percent and the diameter of the feed rolldecreased only by about 0.008 inches. This clearly indicated that feedroll glazing could be prevented through the utilization of an abrasivemember for removing contamination from the feed roll in order tomaintain the roughness thereof substantially constant, i.e., thecoefficient of friction is maintained substantially constant at apreselected value. As hereinbefore indicated, the biasing means or coilspring 84 is prewound, in this way, when feed rolls l4 and 16 rotate ina counter clockwise direction to buckle the uppermost sheet of stack 28,the spring is unwound and there is no rubbing action on feed rolls l4and 16. However, when feed rolls 14 and 16 rotate in a clockwisedirection, to advance the uppermost sheet from stack 28, coil spring 84is wound and yieldingly prevents cylindrical member 80 from rotating.Thus, under these circumstances, there is a rubbing action betweensandpaper coating 82 and feed rolls 14 and 16. The characteristics ofthe spring, in order to insure that the cylindrical member 80 is free torotate when feed rolls l4 and 16 buckle the sheet and prevent rotationwhen feed rolls 14 and 16 advances the sheet, are as follows: preferablycoil spring 84 should have an inner diameter of 0.371 inches; a wirediameter of 0.020 inches; and a free length of 0.130 inches with aboutfour turns. The spring depicted in the drawing is right handed. Whilethe invention has been described in connection with a coil spring, oneskilled in the art will appreciate that the invention is not necessarilyso limited and that other suitable means such as a retractable stop pinmay be provided for preventing the cylindrical member from rotating inone direction while permitting the cylindrical member to rotate in theopposite position.

In recapitulation, the present invention maintains a preselectedfrictional force between the feed rolls and each successive sheet to beadvanced by removing contamination such as paper fibers and/or tonerparticles embedded therein and maintaining the roughness thereofsubstantially constant. Moreover, due to the intermittent rubbing of thesurface of the feed rolls, ozone is less likely to penetrate the surfacethereof and damage the feed rolls. Hence the apparatus. of the presentinvention has been found to substantially increase the useful life ofnatural rubber feed rolls.

Thus, it is apparent that there has been provided in accordance with thepresent invention, apparatus that fully satisfies the object, aims andadvantages set forth above. While the invention has been described incon- 5 junction with specific embodiments thereof, it is evident thatmany alternatives, modifications and variations will be apparent tothose skilled'in the art in light of the foregoing description.Accordingly, it is intended to embrace all such alternatives,modifications and variations as fall within the spirit and broad scopeof the appended claims.

What is claimed is:

1. An apparatus for forwarding successive sheets from a stack of sheetmaterial in a storage compartment, including:

means for separating and advancing successive sheets from the stack,said separating and advancing means having an outer surface portionthereof contacting each successive sheet to be forwarded therefrom;

a support member mounted movably in the storage compartment;

a cylindrical member mounted rotatably on said support member, saidsupport member being pivotable to gravity urge said cylindrical membertoward said separating and advancing means positioning said cylindricalmember in rubbing engagement therewith; and

biasing means for yieldingly preventing said cylindrical member fromrotating in one direction while permitting said cylindrical member torotate in the opposed direction, the rubbing of said cylindrical memberagainst said separating and advancing surface when said cylindricalmember is substantially prevented from rotating maintaining theroughness of said separating and advancing means substantially constantto retain about a preselected frictional force between said separatingand advancing means and each successive sheet permitting continuouslyefficient separation and advancement thereof.

2. An apparatus as recited in claim 1, wherein said cylindrical memberincludes frictional means for sliding abrasively over the outer surfaceportion of said separating and advancing means when said biasing meansyieldingly prevents said cylindrical member from rotating.

3. An apparatus as recited in claim 2, wherein said frictional meansincludes a sandpaper coating disposed on the outer peripheral surface ofsaid cylindrical member.

4. An apparatus as recited in claim 2, wherein said cylindrical membermaintains the coefficient of friction of said separating and advancingmeans preferably in the range of from about 2.35 to about 2.97.

5. An apparatus for maintaining the peripheral surface portion of arotatable feed roll used in a sheet forwarding mechanism at about apreselected surface finish, including:

a movable support member cooperating with the sheet forwardingmechanism;

a cylindrical member mounted rotatably on said support member, saidsupport member being pivotable to gravity urge said cylindrical membertoward the feed roll positioning said cylindrical member in rubbingengagement therewith; and

biasing means for yieldingly preventing said cylindrical member fromrotating in one direction while permitting said cylindrical member torotate in the opposed direction the rubbing of said cylindrical memberagainst said feed roll when said cylindrical member is substantiallyprevented from rotating maintaining the roughness of the feed rollsubstantially constant to retain about a preselected frictional forcebetween the feed roll and each successive sheet permitting continuouslyefficient separation and advancement thereof.

6. An apparatus as recited in claim 5, wherein said cylindrical memberincludes frictional means for sliding abrasively over the outerperipheral surface of the feed roll when said biasing means preventssaid cylindrical member from rotating.

7. An apparatus as recited in claim 6, wherein said frictional meansincludes a sandpaper coating disposed on the outer peripheral surface ofsaid cylindrical member.

8. An apparatus as recited in claim 6, wherein said cylindrical membermaintains the coefficient of friction of the feed roll preferably in therange of from about 2.35 to about 2.97.

9. An apparatus for seriatim feeding of sheets from a stack of sheetmaterial housed in a storage compartment, including:

means for separating and advancing successive sheets from the stack,said separating and advancing means having an outer surface portionthereof contacting each successive sheet to be forwarded therefrom;

a support member mounted movably in the storage compartment;

an abrasive roller mounted rotatably on said support member, saidsupport member being movable to position said abrasive roller incontinuous engagement with the outer surface portion of said separatingand advancing means; and

means for controlling the rotation of said abrasive roller relative tosaid separating and advancing means, said control means being adapted tosubstantially prevent said abrasive roller from rotating in onedirection while permitting said abrasive roller to rotate in the opposeddirection, said abrasive roller, when substantially prevented fromrotating sliding abrasively over the outer surface portion of saidseparating and advancing means, thus maintaining the roughness of saidseparating and advancing means substantially constant to retain about apreselected frictional force between said separating and advancing meansand each successive sheet permitting continuously efficient separationand advancement thereof.

1. An apparatus for forwarding successive sheets from a stack of sheetmaterial in a storage compartment, including: means for separating andadvancing successive sheets from the stack, said separating andadvancing means having an outer surface portion thereof contacting eachsuccessive sheet to be forwarded therefrom; a support member mountedmovably in the storage compartment; a cylindrical member mountedrotatably on said support member, said support member being pivotable togravity urge said cylindrical member toward said separating andadvancing means positioning said cylindrical member in rubbingengagement therewith; and biasing means for yieldingly preventing saidcylindrical member from rotating in one direction while permitting saidcylindrical member to rotate in the opposed direction, the rubbing ofsaid cylindrical member against said separating and advancing surfacewhen said cylindrical member is substantially prevented from rotatingmaintaining the roughness of said separating and advancing meanssubstantially constant to retain about a preselected frictional forcebetween said separating and advancing means and each successive sheetpermitting continuously efficient separation and advancement thereof. 2.An apparatus as recited in claim 1, wherein said cylindrical memberincludes frictional means for sliding abrasively over the outer surfaceportion of said separating and advancing means when said biasing meansyieldingly prevents said cylindrical member from rotating.
 3. Anapparatus as recited in claim 2, wherein said frictional means includesa sandpaper coating disposed on the outer peripheral surfaCe of saidcylindrical member.
 4. An apparatus as recited in claim 2, wherein saidcylindrical member maintains the coefficient of friction of saidseparating and advancing means preferably in the range of from about2.35 to about 2.97.
 5. An apparatus for maintaining the peripheralsurface portion of a rotatable feed roll used in a sheet forwardingmechanism at about a preselected surface finish, including: a movablesupport member cooperating with the sheet forwarding mechanism; acylindrical member mounted rotatably on said support member, saidsupport member being pivotable to gravity urge said cylindrical membertoward the feed roll positioning said cylindrical member in rubbingengagement therewith; and biasing means for yieldingly preventing saidcylindrical member from rotating in one direction while permitting saidcylindrical member to rotate in the opposed direction the rubbing ofsaid cylindrical member against said feed roll when said cylindricalmember is substantially prevented from rotating maintaining theroughness of the feed roll substantially constant to retain about apreselected frictional force between the feed roll and each successivesheet permitting continuously efficient separation and advancementthereof.
 6. An apparatus as recited in claim 5, wherein said cylindricalmember includes frictional means for sliding abrasively over the outerperipheral surface of the feed roll when said biasing means preventssaid cylindrical member from rotating.
 7. An apparatus as recited inclaim 6, wherein said frictional means includes a sandpaper coatingdisposed on the outer peripheral surface of said cylindrical member. 8.An apparatus as recited in claim 6, wherein said cylindrical membermaintains the coefficient of friction of the feed roll preferably in therange of from about 2.35 to about 2.97.
 9. An apparatus for seriatimfeeding of sheets from a stack of sheet material housed in a storagecompartment, including: means for separating and advancing successivesheets from the stack, said separating and advancing means having anouter surface portion thereof contacting each successive sheet to beforwarded therefrom; a support member mounted movably in the storagecompartment; an abrasive roller mounted rotatably on said supportmember, said support member being movable to position said abrasiveroller in continuous engagement with the outer surface portion of saidseparating and advancing means; and means for controlling the rotationof said abrasive roller relative to said separating and advancing means,said control means being adapted to substantially prevent said abrasiveroller from rotating in one direction while permitting said abrasiveroller to rotate in the opposed direction, said abrasive roller, whensubstantially prevented from rotating sliding abrasively over the outersurface portion of said separating and advancing means, thus maintainingthe roughness of said separating and advancing means substantiallyconstant to retain about a preselected frictional force between saidseparating and advancing means and each successive sheet permittingcontinuously efficient separation and advancement thereof.